docs: document block-pinned component reads

[layertau]

Summary

• Add WAVS skill guidance to treat trigger/event block height as the canonical snapshot for related on-chain reads.
• Note that EVM/Cosmos/RPC reads should pass block number/height when supported and avoid mixing historical trigger data with latest-state reads.
• Call out the oracle updatedAt/RPC snapshot mismatch class of bugs.

Testing

• Docs-only change; no automated tests run.